Secondary electric clock



(ModeL) W. B. HARVEY.

SECONDARY ELECTRIC CLOCK. No. 377,895. Patented Feb. 14,1888.

WITNESSES: TOR:

ATTORNEYS-L i UNITED STATES PATENT OFFICE.

WIET B. HARVEY, OF MEMPHIS, TENNESSEE.

SECONDARY ELECTRIC CLOCK.

SPECIFICATION forming part of Letters Patent No. 377,895, dated February14, 1888.

Application filed August 25, 1885. Serial No. 175.300. (Modcl.)

To all whom it may concern.-

1 3e it known that I, WrR'r B. HARVEY, a cit zen of the United States,residing at Memphis, in Shelby county, State of Tennessee, have inventedcertain new and useful improvements in Secondary Electric Clocks, ofwhich the following is a full, clear, and exact description.

The object of this my present invention is to lmprove the construction,simplify the action, andincrease the efficiency and certainty ofoperatlng, correcting, and synchronizing the hands of secondary electricclocks upon and by means of the same line wire or circuit over which thesignals that are to operate the hands once per minute or oftener aretransmitted; and to these ends it consists in certain details l ofconstruction, combinations of elements, and

peculiarities of arrangement and operation, that will be specified moreparticularly in the claims at the end of this specification.

My invention consists of a secondary electric clock containing, inaddition to the usual electro-magnet, armature, gears, &c.,nsed forpropelling the hands forward, a polarized armature, two pins, screws, orcatches so placed n relation to each other and the arbors carrying thehands that the polarized armature will at all times be in a position toarrest either of said pins, screws, or catches, thereby arresting thehands at certain points on the face of their dials during eachrevolution for the purpose of correcting or synchronizing.

My invention is more especially designed to operate 1n acircuit where aregulator or master-clock causes the said circuit to be closed for ashort space of time during each minute, preferably the last second ofeach minute. Reference is had to the accompanying draw- 1ngs, forming apart of this specification, in which a diagrammatic side View of myimproved secondary electric clock is shown.

The minute-hand A is mounted on the end of a spindle, B, surrounded by asleeve, 0, carrying the hourhand D and provided with a cog-wheel, D,engagingwith a pinion, E,

on the shaft E, carrying a cog-wheel, F, en-

gaging with a pinion, F, on the spindle B, which carries on its otherend a ratchet-wheel, G, on the edge of which plays a pawl, H, piv= otedon an armatureiever, J, which is pivoted near the ends of the cores ofan electromagnet, K, said armature being pulled away from the said coresby a spiral or other spring, J, when no current is flowing through thecoils of the electro-magnet, all so mounted in relation to each other asto operate the hands of a secondary electric clock in the usual mannerby means of an electric current.

A permanent magnet, L, is secured to the clock-case, on one pole ofwhich is secured an electromagnet, I, and on the other pole the armatureM is pivoted in such a manner as to swing freely between the ends of thecores of the electro-magnet I. The armature M is thus polarized and notaffected by the opening or closing of the circuit, butonly by thereversals. This principle is well understood by electricians or othersversed in the art. A pin, N, is placed transversely through thepolarized armature M and projects from opposite sides between twocheck-screws, O O. A screw, pin, or catch, P, is carried by the sleeve0, and another, R, by the collar Q on the spindle B. The polarizedarmature M is located in relation to these pins so that it lies eitherin the one or the other path at all times, as they revolve around withthe spindles, sleeves, and hands, and will at a certain point of arevolution of either hand prevent its passage until it is removed bybeing placed in the path of the other. The line wires or circuitconnecting the secondary electric clock with the masterclock areconnected to the posts I) b, which are in connection electrically withthe electromagnet I and electromagnet K by the wire 0.

It will readily be understood that when the polarized armature M engageseither pin 1? or It both bands will be locked and cannot proceed untilreleased, although signals may con; tinue to flow through the circuit.

When secondary electric clocks are placed at a distance and out of sightof the masterclock, as is usually done, and a number of them included ina circuit, there is no way to tell where the hands point to 011 the faceof the dials, and if a certain one accidentally fell behind, which fromvarious causes often occurs, it continues that much out of time orbehind the others until an inspector or some one corrects it by hand.There is also no means whereby one at the central station can knowwhether or not the secondary clocks are correct at any time. Myinvention meets these requirements and allows the secondary electricclocks to be corrected, synchronized, and to cause all the hands topoint to the same time or point on the faces of their several dials.

It will easily be seen that if two or more secondary electric clocks areplaced in the same circuit,whose pins are arranged at exactly the samepointthat is, arranged to be engaged when their hands reach a certaintime or point on their dials-while one or more may be faster or slowerthan others, if a sufficient number of signals are transmitted to them,each one will respond to every such signal until that time or point isreached, and then stop responding, although the one that is slower willcontinue responding. A time therefore must come when all secondaryelectric clocks have ceased following the signals, when the hands willall point to the same time or point on the faces of their several dials.

For various reasons I prefer to select XII as the time to synchronizethe hour-hands, and the thirty-minute mark of an hour the minute-hand. Ialso prefer thata synchronizing take place once every twelve hours. Ifthis time is selected, it allows one pin to revolve out of the way, sothat when the other is engaged by the polarized armature M nothing willbe in the way to prevent said armature being removed from out of thepath of the engaged pin. I also prefer that the current from the mainbattery be of such a direction or polarity as to incline the polarizedarmature M in the path of the pin carried by the sleeve carrying thehour-hand as its normal position, and let it remain that way for twelvehours or reversed only long enough to effect a correction. This willprevent'having to shift it back and forth to enable the pin on theminute-hand arbor to continue its rotation, as it is evident that when apin is engaged by the said polarized armature, if not shifted out of itspath, then the hands must stop. By working the battery in this positionthe attention required is greatly lessened, as the current has only tobe reversed once in twelve hours to enable the secondary hands tocontinue rotating, wherein if it was worked in the opposite direction orposition it would have to be reversed once per hour.

To correct or synchronize a circuit comprising one or more secondaryelectric clocks whose pins or catches have been previously so placed inrelation to each other as to prevent the hands passing a certain pointon the face of their dials, said point being the same, the operation isas follows:

' As an illustration, say the correct time is ten minutes before twelveand that some of the secondary electric clocks were faster, some slower,and some correct as to that time. The first thingto be doneis todisconnect the masterclock and apparatus responding to its impulses orsignals, and insert in circuit a convenient hand-key or circuit-closerand a polechanger or eurrent-reverser, placing the latter in such aposition as to cause the current to incline-polarized armature M in thepath of pin 1?. Then with the circuit-closer close the circuit once persecond, or oftener, for several minutes. The correct secondary clocksw1ll be thrown out of time for the first few signals; but this will notmake much difference, as they will not remain so for anylength of tlme.The fast clocks, if over a few minutes fast, may, as far as theoperation is concerned, be considered as slow, and will respond tosignals until a suificient number has been made by the circuit-breakerto bring their hands up to XII mark on their several dials. Now, 1f youhave been quick with the synchronizing, it will be necessary to allowthe master-clock to catch up, as the expression goes. After themaster-clock hands point to the time of XII, and before it has reachedXII and one minute, replace the master-clock and apparatus in c rcuit,allowing the pole-changer to remaln in also. Reverse the current fromits normal direction or polarity, and leave it so until 12.30 oclock isreached by the master-clock, when, with the polechangers till in thatposition, operate the circuit-closer as before for, say, half a minute,then reverse the current, and when the master-clock closes the circuitfor the thirtyfirst minute of the hour the polarized armature will beremoved from the path of pin R, in addition to the hands'responding tothe signal, which they do as soon as they are released by said polarizedarmature M. I prefer the polechanger being in the circuit at all times,and the master-clock transmitter-points and those of the circuit-closerbeing so arranged as to each other that either one will close thecircuit when operated-a principle well understood by those versed in theart.

Owing to the fact that when a secondary clock is not very carefullyconstructed, there being a sufficient amount of lost motion, as it were,between the gearings of the two hands, I find that in synchronizing bymeans of engagingpin P the minute-hand may go a minute or two beyond theXII mark of the dials; but this deviation cannot occur when pin R isengaged by the polarized armature M.

A synchronizing of the secondary clocks may be had at any time duringthe day or night; but by selecting some particular time to do so, andarranging the pins in each one to that time, the interference withclocks that are already correct may be avoided.

Experience shows that a secondary electric clock seldom needs orrequires correcting for more than a few minutes, although sometimes itbecomes necessary to correct one several hours. Any correction of lessthan sixty minutes may be had once per hour by any one at the centraloffice.

Having now fully shown and described my invention, what I desire toclaim, and secure by Letters Patent, is

l. A secondary electric clock provided with an electro-magnetarrangement for operating the hands and a polarizing electromagnet andpolarized armature for arresting one or hands of the clock, of apolarized electro magnet and polarized armature, the coils of the saidpolarized electro-magnet being in the circuit with the coils of thehand-operating electro-magnet and the armature adapted to engage theprojection on the spindle of the hour-hand, substantially as hereinshown an described.

3. The combination, with an electric clock having projections on thespindles of the hour and minute hands and an electro-magnet foroperating the hands of the clock, of a polarized electro-magnet, andpolarized armature the coils of the said polarized electro-xnagnet beingin the circuit with the hand-operating electro-magnet and the polarizedarmature hand, a sleeve surrounding the spindle and a carrying thehour-hand, and an electro-niagnet and intermediate mechanism foroperating the hands from said electro-magnet,of projections on thespindle and sleeve, a polarizing electromagnet and polarized armature,the said polarizing electro-magnet coil or coils being in the sameelectric circuit with the hand-operating electro-magnet coil or coils,and the'polarized armature adapted to engage the said projections forthe purpose of synchronizing the hands, substantially as herein shownand described.

W. B. HARVEY.

\Vitnesses:

J. S. GALLowAY, O. T. SMITH.

